A tensioner as referred to in this specification is utilized for imparting a predetermined tension to a chain, etc., which is adapted to transmit a torque from a crankshaft of an engine to a cam shaft. Such a tensioner includes a type in which a plunger is slidably received within a housing so as to be urged to protrude from the housing, and a ratchet is mounted to said so as to mesh with a rack formed on the plunger in order to prevent the plunger from retreating.
Conventionally, in such a tensioner, the pitch of the teeth of the ratchet is designed to be identical with that of the teeth of the rack. Thus, if the pitch of one of those members is varied, the other of the members needs be made anew so that there is a matching in the pitches of the respective teeth.
Ratchets are generally made by sintering. Consequently, every time there occurs a design change to the ratchet, remaking of the moldings becomes necessary, with the resultant higher manufacturing costs.
There exists a ratchet having a single tooth; however, it is not usually sufficient in terms of the strength.